1. Field of the Invention
The invention relates to self-retaining bolt assemblies; and, more particularly, to an adjustable diameter bolt assembly for use in aircraft and other similar installations.
2. Description of the Prior Art
Self-retaining bolts are well known in the aircraft industry. Such bolts are mounted in one panel and adapted to be selectively coupled to and disengaged from a mating member mounted in an adjacent panel. Such prior art bolts include means thereon for retaining the bolt to the panel in which it is installed so that it can't fall out during vibration or the like even if it is not connected to its mating member and for allowing subsequent easy release therefrom. One type of prior art bolt is disclosed in U.S. Pat. No. 4,759,671. In this patent, a self-retaining bolt is disclosed having means for retaining the bolt to the panel in which it is installed without weakening the bolt while permitting easy release therefrom. Such means is easy to manufacture and install, require relatively few working parts and does not require orientation in a fixed direction for assembly.
However, the holes in the panels in which such bolts are installed vary in internal diameter. It is difficult to provide a bolt having a shank diameter that tightly fits in all such panel holes. There is thus a need for filling the spacing between the bolt shank and the hole walls of the panel in which the bolt is installed. Bushing segments are known which are used to fill such spacing, such as those disclosed in U.S. Pat. No. 3,192,820 to Pitzer. In U.S. Pat. No. 3,192,820 to Pitzer, there is disclosed a quick release pin having a plurality of male and female rings or bushings which, when compressed axially as a result of a compressive force applied to one end of the bushings, forces the male rings to contract and the female rings to expand to assume a larger diameter. That is, the effective diameter of the quick release pin can be increased after the pin is installed in a hole or opening in an installation. In like manner, the effective diameter of the pin can be reduced (or returned to its original diameter) when it is desired to remove the pin from the installation. There is a need for applying such bushing segments to a self-retaining bolt, as disclosed in U.S. Pat. No. 4,759,671, while protecting the pawl during the torquing of the bushing segments. In pending U.S. patent application Ser. No. 07/816,654, filed Jan. 3, 1992, commonly assigned, there is discussed a self-retaining adjustable diameter bolt assembly including a bolt having a head, a shank, and a threaded end adapted to be inserted into aligned holes in a pair of abutting panels for subsequent coupling to a nut on the blind side of the panels. The bolt includes a pawl engaging one side of the panel in which the bolt is inserted with the head thereof on the opposite side of the panels. A plurality of bushing segments are mounted on the bolt shank, the pawl extending through an opening in the segment adjacent the threaded end of the bolt shank. A nut, having a skirt portion, is threaded onto the threaded end driving the segments forward and filling the spacing between the holes and the bolt shank. The skirt portion of the nut overlies the pawl and protects the same. The nut can be fully torqued to cause complete radial expansion of the bushing segments in the aligned panel holes before bottoming out against the panels.
In this assembly, the bushings must be manufactured to exact tolerances and are thus costly to manufacture. There is a need for reducing the number of bushings while retaining the inventive features disclosed in the pending application. Further, in the assembly in the pending application, the bushing segment 44 therein through which pawl 22 protrudes must be peened about the opening in segment 44 surrounding pawl 22 to prevent its withdrawal. There is a need for eliminating the necessity of such peening yet trapping the pawl in the segment. Finally, the pawl 22 in the pending application, and the hole in the bolt in which the pawl 22 is disposed must be machined with mating configured parts to orient the pawl in the proper operative direction. There is a need to eliminate such mating configured parts while retaining the proper orientation of the pawl.